1. Technical Field
This invention relates to automated reading of diagnostic reagents. More specifically, the present invention pertains to the placement of non-visible infrared (“IR”) barcodes either within or adjacent to traditional color barcodes printed on reagent media to provide additional calibration and other information for a reagent lot.
2. Background Information
Many instruments have been developed to measure the presence and quantity of analytes in various biological samples such as, for example, urine, blood, saliva, extracts of mucus or tissue, etc. Typically, a sample liquid is applied to a surface, or carrier, containing reagents that react with the analyte. The reagents produce a detectable response that may be measured and related to the amount of analyte present in the sample.
Dry reagents are commonly used for diagnostics and may be read with an instrument, such as an optical reader and/or electrochemical reader. There are several conventional formats of dry reagent media including, for example, strip format, card format, and micro-fluidic chip format. There are also a number of possible configurations and within each particular format.
For example, sample media in the form of a test strip usually has one or more test areas spaced along the length thereof, with each test area being capable of undergoing a color change in response to contact with a liquid specimen. The liquid specimen usually contains one or more constituents or properties of interest. The presence and concentrations of these constituents or properties are determinable by an analysis of the color changes undergone by the test strip. Usually, this analysis involves a color comparison between the test area or test pad and a color standard or scale. In this way, reagent test strips assist physicians in diagnosing the existence of diseases and other health problems.
Color comparisons made with the naked eye can lead to imprecise measurement. Today, strip reading instruments exist which employ reflectance photometry for reading test strip color changes. These instruments accurately determine the color change of a test strip within a particular wavelength range or bandwidth. Examples of such instruments include those sold under the CLINITEK® trademark (e.g., the CLINITEK ATLAS® and the CLINITEK® 500) by Siemens Healthcare Diagnostics Inc (Tarrytown, N.Y.) and/or as disclosed in U.S. Pat. Nos. 5,408,535 and 5,877,863, both of which are fully incorporated by reference herein. These instruments are typically used to detect colors associated with a urine specimen on a MULTISTIX® (Siemens) reagent strip, or on relatively large reagent strip rolls for high volume automated analysis such as provided by the CLINITEK ATLAS® Automated Urine Chemistry Analyzer.
In the past, color barcodes were used to convey reagent configuration to the read instrument. Generally, the color barcodes are placed on the dry reagent carrier and read by the instrument prior to analyzing the sample. Two methods are in known use for Point-of-Care instrumentation: 1) Large color bars (e.g., 0.2 inch) are used with the patterns of colors describing a reagent configuration; and 2) common black/white barcodes on test media such as cassettes or strips, in which the size/shape and sequence of the bars is used to encode the reagent configuration. The use of either one of these barcodes must substantially match software in the instruments, otherwise an error will result. The instruments are programmed to only recognize a number of barcode color configurations, and to adjust accordingly.
As technology in this field continues to advance, the need arises to convey additional and more sophisticated information to the read instrument. For example, newer read instruments have functionality and capabilities beyond those of their predecessors and require additional information to utilize that functionality. Accordingly, there is a need to add additional barcode configurations and colors to the color barcodes. However, this is not easily achieved as the addition of additional bars or colors would cause read errors in the older machines. The problem is one of backward compatibility. New reagent carriers or media with the additional information would generally cause read errors on older generation machines. Imprinting standard barcode information in a varied configuration or color would change the reflectance of the barcode and backward compatibility would be broken. Thus, it is generally required to either upgrade the instrument or the instrument's firmware, which disadvantageously tends to increase cost.
A need therefore exists for sample media that address the aforementioned drawbacks.